Method for producing a multilayered preform and a preform

ABSTRACT

The invention relates to a multi-component injection molding method for producing a sleeve-shaped preform as well as to a perform which has at least two layers, said method comprising at least two process steps including at least two cavities and at least one injection mold core that can be used for both cavities, and wherein during the first process step, the first layer which has at least one first and at least one second area extending partially in the circumferential direction of the preform, is injected onto the injection mold core within the first cavity, with the second area having a substantially lower layer thickness than the first area, and during the second process step, the second layer is deposited on the first layer which is located on the injection mold core in the second cavity in such a way that only the second area of the first layer is completely covered by the second layer, or during the first process step, the first area of the first layer is deposited partially on the injection mold core within the first cavity, with the remaining areas being covered by the second layer during a second process step within a second cavity.

This application claims priority under 35 USC 119(a) to German PatentApplication No. 10-2010-036-103.8 filed on Sep. 1, 2010, which isincorporated by reference in its entirety herein.

The present invention relates to a multi-component injection mouldingmethod for producing a sleeve-like/sleeve-shaped preform as well as to amultilayered preform according to the preambles of claims 1 and 9.

It is known that commercial preforms are used for producing a plasticcontainer such as for example a PET drinks bottle, by applying a hotmedium onto the performs, for example in a stretch/blow moulding system,and subsequently blowing up and moulding the preforms into the desiredcontainer within a mould.

To this end, these preforms only have a single layer, so that thecontainers subsequently moulded therefrom have a correspondingly thinwall.

Further, the commercial containers have a wall thickness that isessentially the same in the circumferential and the longitudinaldirections, whilst, if necessary, the bottom area may have a slightlygreater wall thickness than the remaining areas, which is the result ofthe expansion of the preform in the stretch/blow moulding system. Thewall thickness of the container, which is essentially identical in thecircumferential and the longitudinal directions, is achieved due to theessentially uniform wall thickness or layer thickness of said one layerof the preform.

The preform is obtained as a result of injecting, in a single-componentinjection moulding method, only one plastic layer onto a core located ina cavity or in an injection mould. Since the core is centricallypositioned in the cavity, it is surrounded prior to the injection by adefined air space over its entire circumference, which air space iscompletely filled during the injection process by the first plasticlayer and later consequently determines the wall thickness of thepreform and thus also the wall thickness of the container which is thenproduced from the preform.

The application of a second layer onto a first layer during theproduction of a preform by means of a two-component injection mouldingprocess requires specific knowledge for example of the expansioncoefficients of the layers used, said layers usually being plasticlayers such as PET layers.

For example, if a container is to consist of two layers which havedifferent colourings from each other, the preform will correspondinglyhave to consist of at least two layers of different colours.

In order to make it possible for the two layers to have differentcolourings, chemical additives such as carbon black are admixed to eachplastic layer which may have a substantial effect on the expansionbehaviour of the plastics during the stretching and blow mouldingprocess.

Accordingly, it may occur that a first layer expands at a slower ratethan a second layer and consequently rips or is damaged during thecontainer production process, as a result of which the container can nolonger be used for example for containing a medium.

Also the strong or inseparable bond of the two layers to each other, inparticular during the stretching/blow moulding process, is anindispensable precondition for the production of a two-colour preform orcontainer.

WO 2008/125709 A1, for example, describes a method for producing atwo-component preform as well as the preform itself. The injectionapparatus used has two injection moulds, the first injection mould ofwhich has an element for spacing the core from the mould wall. To startwith, the first layer is deposited on the core in the first injectionmould, and subsequently a second layer is poured over it in the secondinjection mould. Both layers may have different colourings. The preformwhich has a customary shape that is generally known in the prior art, ismade from PET or PP, and additives such as titanium oxide or carbon areused for the colouring of the individual layers. The second layer mayextend over the entire circumference either of the entire preform orjust over a defined bottom area of the preform. If the second layercompletely covers the first layer, it will serve as a light or gasbarrier, whereas the second layer which is attached to the closed bottomarea of the preform, is merely used for reinforcing the bottom area, forexample due to the second layer including a different material to thefirst layer. A specific colouring or an individual colour scheme or areinforcement of defined partial areas of the preform by means of thesecond layer is not possible with the method disclosed in WO 2008/125709A1.

Accordingly, it is the object of the present invention to provide amethod for producing a multilayer preform as well as a perform, whichenables an individual colouring for an unambiguous identification of thecontainers produced from the preform as well as predefined reinforcedpartial areas for stabilisation or for better usability of thecontainers made from the preforms to be achieved.

According to the present invention, this object is achieved by means ofa method as claimed in claim 1 and a preform as claimed in claim 9.

The multi-component injection moulding method for producing asleeve-like preform according to the invention, which includes at leasttwo layers, comprises at least two process steps including at least twocavities and at least one injection mould core usable for both cavities,wherein during the first process step, the first layer which has atleast one first area and at least one second area partially extending inthe circumferential direction of the preform, is injection-moulded ontothe injection mould core within the first cavity. The second area has asubstantially reduced layer thickness compared to the first area. Duringthe second process step, in the second cavity the second layer isdeposited on the first layer located on the injection mould core in thein such a way that only the second area of the first layer is completelycovered by the second layer, or during the first process step, the firstarea (2 a) of the first layer (2) is partially deposited on theinjection mould core within the first cavity and the remaining areas arecovered by the second layer (3) during a second process step within asecond cavity.

A multi-component injection moulding method is characterised for exampleby the production of at least one two-layer plastic preform, however, itis also possible for more than two layers to be arranged on top of eachother in a radial direction or next to each other in the circumferentialand/or longitudinal direction(s).

This means that the at least one first layer, which forms the innersurface of the preform, does not necessarily have to be formed from afirst continuous layer. It is also conceivable for the first layer toconsist for example of two layers having different materialcompositions, wherein for example the one first layer forms the upperopen area for example with a thread, whereas the second first layerforms a bottom closed area of the preform and both layers are adjacentor adhere to each other in a predefined area, in order to form thesleeve-like shape of the preform as is generally known in the prior art.The same applies also to the formation of the second layer or a possiblethird or fourth layer.

Consequently, the at least two layers may be deposited in such a waythat they are not arranged on top of each other in the radial directionbut next to each other. Thus, these two layers form a single uniform andcontinuous layer, wherein the second layer fills those areas on theinjection mould core, that were not covered by the first layer.

This requires an exact gating/sprue of the second layer on the joint,i.e. onto the transition area of the first layer, in order to avoid theformation of tears or unevenness during the blow moulding and stretchingof the preform into a container.

In this way it is possible to produce a preform made from at least twocomponents, which has a very low layer thickness and at the same timeensures customised colouring.

The number of layers that form the preform is not limited. However, inorder to enhance the understanding of the subsequent description, it isassumed that only two layers are used.

It is further noted that not only the sleeve-like shape of the preform,which is generally known from the prior art, can be produced in amulti-component injection moulding process, but any desired shape. Theshaping only depends on the shape of the injection mould or the cavityand the shape of the injection mould core or the core.

Moreover, the invention is not limited to just two process steps, sinceit is quite conceivable that for instance a third and fourth layerscould be deposited on the first or second layer of the preform in athird or a fourth process step.

During a first process step, the injection mould core or core isintroduced into a cavity which is closed for example by a correspondingdesign at one end of the core or by means of another device which is notexplained in more detail herein.

Such a system may for example include a plurality of cavities orinjection moulds which may be formed depending on the manufacturer's orthe client's requirements either to be identical or to be different fromeach other. Thus it is possible that a so-called multi-componentinjection tool includes a plurality of injection moulds or cavities, inorder to mould a large number of preforms at the same time.

If the cavity is hermetically sealed, a plastic mass forming the firstlayer, which may include additives as a function of the desiredcolouring, is injected into the first cavity under a predefinedpressure. The plastic mass either expands completely within the spaceavailable to it around the core, in order to form in this way acontinuous first layer of the preform, or the first layer expands on thecore only up to a predefined area, in order to cover only this area ofthe preform, so that the core is covered by the first layer onlypartially during the first injection moulding process or the firstprocess step.

If the first variant is selected, namely that the first layer completelyexpands on the core within the first cavity in order to form acompletely continuous first layer, it is possible that the first layer,by way of a predefined shaping of the first cavity, includes a first andsecond areas, wherein the second area having a substantially lower layerthickness or wall thickness of the layer than the first area.

This means that second areas are formed for example by protrusions andfirst areas are formed for example by depressions, which are arranged inthe cavity and which extend from the inner surface of the cavityessentially in a radial direction towards the inside (protrusions) ortowards the outside (depressions), in order to reduce (protrusions) orincrease (depressions) in this way the deposition of material on thispredefined area.

Thus, it is possible for the first cavity to have either protrusions ordepressions or alternatively both protrusions and depressions at thesame time, and in the latter case the depressions will then have to bearranged directly on the protrusions, in order to avoid the formation ofa third intermediate area.

In a preferred embodiment example, the cavity has protrusions in definedareas of the cavity so as to be able to form partially occurring secondareas of the first layer.

The protrusions and depressions may extend in any desired direction andlength in the circumferential and/or longitudinal direction(s) of theinternal surface of the cavity. They are arranged depending oncustomers' requirements with regard to the colouring of the futurecontainer on the internal surface of the cavity.

Moreover, it is possible for the protrusions and depressions to extendalso in any desired length radially inwards or outwards, so that forexample in the case of at least two protrusions being present in acavity, both protrusions have a different extension in the radialdirection towards the inside.

Further, the radial extension of the protrusion towards the inside forexample over the length of a protrusion may be different, so that layerthickness differences within the second area of the first layer occur.The same may also apply to the depressions.

According to the second variant, wherein the first layer may expand onlypartially on the core during the first injection process within thefirst cavity, flowing of the first layer into certain areas of thecavity through walls or the like of the cavity is prevented for exampleby means of a cavity shaped as per the definition of the requiredcolouring. Accordingly, the cavity has for example at least oneprotrusion which extends from the inner surface of the cavity radiallytowards the inside and is so pronounced that the protrusion rests on thecore at least in sections, in order to interrupt a flow of the firstlayer in this position. In this connection it is further conceivablethat to this end, the cavity may include also several gate areas, sothat the partial first layer areas can be formed essentially at the sametime.

According to the first variant, once the first layer having at least onefirst area and at least one second area has been deposited orinjected/spray-applied or poured onto the core, the second layer isdeposited onto the first layer in a second process step within a secondcavity. To this end, however, the second layer is injected/spray-appliedonly on or in to the second areas of the first layer, which were formedby the protrusions, in such a way that the second layer and the firstareas of the first layer form a planar external surface of the preform.

To this end, the second cavity preferably has an inner surface which isdirectly adjacent to the outer surface of the first area of the firstlayer, i.e. it touches it so that during the deposition of the secondlayer, no plastic mass of the second layer can be injected/spray-appliedonto the outer surface of the first area of the first layer.

Further, the second cavity may, depending on the arrangement of thesecond areas of the first layer, include several injection openings,through which a plastic mass provided for this purpose isinjected/spray-applied onto each second area. In this context, alsodifferent plastic masses having the most varied material compositionsmay be used, which will later impart to the container either amulti-coloured colour scheme or predefined properties such as forexample an enhanced feel when a first defined area is touched, and asofter mass in a second area for a reliable standing of the container ona slippery surface.

As materials for the first and/or the second layer(s) according to thefirst and second variants, preferably polyethylene terephthalate (PET),thermoplastic elastomer (TPE) or polyurethane is used.

The second layer is consequently injected/spray-applied onto the secondareas in such a way that the second layer completely fills the secondareas in a radial direction as well as in the circumferential directionof the preform, until the filling level of the second layer reaches thelevel of the outer surface of the first layer (the length which extendsin a radial direction from the inner surface to the outer surface of thefirst area of the first layer).

Thus, the outer surface of the first area of the first layer and theouter surface of the second layer terminate on each other withoutforming a warp or a notch or an overrun region.

Preferably, the remaining heat of the first layer that is still coolingdown is utilised to facilitate the injection/spraying of the secondlayer onto the first layer or onto predefined areas of the first layer.

As a result of the possibility of depositing the second layer onto thefirst layer in a second process step, it is also conceivable that thesecond layer consists of a recyclable material which is generated forexample from a previously used, recycled or melted-down plasticcontainer.

This second layer of the preform, which consists of recycled material,however, will not come into contact with the medium that is laterintroduced into the container that is expanded from the preform. Byusing recycled material as the second layer, cost savings may berealised during the production of the preform.

Once the at least two layers have been deposited on the core for formingthe preform, the preform has a wall thickness which is essentiallyidentical in the longitudinal and the circumferential directions.

Since the second area of the first layer preferably has a layerthickness which continuously reduces in the circumferential and/orlongitudinal direction(s) of the preform at least in sections, thesecond layer consequently has to be injected/spray-applied onto thesecond area of the first layer in such a way that accordingly the secondlayer has a layer thickness which essentially continuously increases inthe circumferential and/or longitudinal direction(s) of the preform atleast in sections, in order to form the counterpart to the second areaof the first layer.

By means of a second layer deposited in this way, which preferably has adifferent colouring or colour to the first layer, it is for examplepossible for the second layer to enable a colour scheme for example fromdark red to be achieved in areas having a great layer thickness to lightred in areas having a small layer thickness, because the layers arestretched by the stretching/blow moulding process in such a way that areduction of the layer thickness and thus a possible reduction of thecolour intensity of the colour of the second layer occurs.

The second area of the first layer has an outer surface as well asjoining areas which are adjacent to the first layer and extendessentially radially outwards, which joining areas connect intimatelywith an inner surface of the second layer as well as with the joiningareas extending radially from the inner surface to the outer surface ofthe second layer due to an adhesive or mechanical bond.

Accordingly, a bond occurs not only between the outer surface of thesecond area of the first layer and the inner surface of the secondlayer, but also between the transitional areas generated by the shape ofthe two areas of the first layer and the edge zones of the second layer.

The transitional areas between the first and second areas are wallsections which occur as a result of the reduced material in the secondarea and as a result of the reduced layer thickness present as a resultof this compared to the first area, which wall sections extendessentially radially from the second area outwards or extend radiallyfrom the first area inwards.

These transitional areas form the joining areas in which the secondlayer meets the first area of the first layer essentially verticallyrelative to the lateral surface of the preform.

However, the joining areas may also correspondingly run out, as a resultof which the area extends for example not radially outwards, but ischaracterised by an area which extends outwardly at an obtuse angle.

According to the second variant, the second layer, which may have adifferent material composition and/or colouring to the first layer, isdeposited on the areas of the core that were not covered by the firstlayer during the first process step in a second process step within asecond cavity. To this end, the second cavity has for example an innersurface which lies directly on top of the outer surface of the firstlayer when the core is introduced into the second cavity with apartially deposited first layer. Thus, an over-moulding of the firstlayer with the second layer may be prevented. To this end, the secondcavity may have a plurality of injection or gate devices arranged on thecavity, in order to introduce the second layer only into the areaswithin the second cavity that are not yet covered by the first layer.

The second layer deposits itself onto the core in a manner identical tothe first layer and bonds with the first layer as a result of the secondlayer flowing up to the edges or the joining areas of the first layer,which joining areas extend outwards from the core in a radial direction,and connects with these joining areas in such a way that these areaswill not rip open or form voids or holes even when the preform is blownup into a container.

According to the second variant, however, it is further conceivable thatthe two layers which are arranged next to each other on the core in theradial direction are deposited on the core at the same time during aprocess step or an injection/spraying process and immediately bond witheach other.

Moreover, the description of two layers is meant to include thepossibility that also three or more layers may be used here, each ofwhich may have different material compositions and/or colourings.

The use of partially different materials for the second layer, forexample in the area of the bottom, may lead to an increase in thestrength or the tensile yield strength. Thus, for example, the bottom ofthe preform or the later container may be specially reinforced or forexample the thread of the preform may have an enhanced heat distortresistance. Accordingly, as a result of the partial arrangement of thesecond layer on the first layer of the preform, stretching in thesepartial areas of the preform may be increased.

In a preferred embodiment, the injection mould core, onto which thefirst and second layers of the preform are injected/spray-applied andwhich is arranged on a rotary plate, is moved into or out of the firstor second cavity in an essentially translational movement of the rotaryplate or of the cavity along a longitudinal axis of the first and/orsecond cavity.

The injection mould core or the core may for example be positioned on arotary plate or a rotary table in such a way that its longitudinal axisis arranged parallel to the rotary axis of the rotary plate.Accordingly, the core extends vertically upwards or downwards from thesurface of the rotary plate.

It is also conceivable that the core is arranged on the rotary plate insuch a way that its longitudinal axis extends vertically to the rotaryaxis of the rotary plate, so that its longitudinal axis is orientatedessentially parallel to the surface of the rotary plate, wherein thecore preferably extending at least in sections beyond the edge of therotary plate.

In both arrangement cases, for example at least two cores may bearranged on a rotary plate, said cores preferably lying opposite eachother on the rotary plate, so that the surface of the rotary plate maybe divided into exactly two equal halves by the arrangement of thecores.

Thus, the rotary plate may be arranged for example before or on thecavities in the injection moulding machine in such a way that thelongitudinal axis of the rotary plate extends either parallel to thelongitudinal axis of the cavity which forms the centre or the centralpoint of the opening or extends through it, or that the longitudinalaxis of the rotary plate extends vertically to the longitudinal axis ofthe cavity.

If the longitudinal axis of the rotary plate extends parallel to thelongitudinal axis of the cavity and accordingly preferably also to thelongitudinal axis of the core, the at least two cavities are arranged inthe injection moulding machine for example next to each other in ahorizontal direction or on top of each other in a vertical direction,and their openings are orientated in the same direction.

However, if the longitudinal axis of the rotary plate is arrangedvertically to the longitudinal axis of the cavity and thus alsovertically to the longitudinal axis of the core, the at least twocavities are arranged for example opposite one another in the injectionmoulding machine, wherein the two openings of the cavity beingrespectively orientated in opposite directions of the respective othercavity opening.

In both arrangement examples of the rotary plate relative to thecavities, the rotary plate may be supported in such a way that as aresult of the translational movement of the rotary plate along thelongitudinal axis of the cavity, the core may be moved into the firstcavity for example prior to the first process step and, upon injectionmoulding of the first layer, back out of the first cavity in a furthertranslational movement of the rotary plate in the opposite directionrelative to the first translational movement of the rotary plate.

For example, once the first layer has been deposited on the core, thecore is transported together with the first layer deposited thereon intoa second cavity.

To this end the injection mould core, onto which the first and secondlayers of the preform are injected/spray-applied and which is arrangedon a rotary plate, is moved between the individual cavities by means ofan essentially rotational movement of the rotary plate about an axiswhich is either parallel or vertical relative to the longitudinaldirection of the cavity.

This means that the rotary plate carries out a rotary movement about therotary axis of preferably 180°, in order to transport or move the coretaken out of the first cavity together with the first layer in front ofthe opening of the second cavity.

Once the core with the first layer is located in front of the opening ofthe second cavity, the rotary plate carries out another translationalmovement in order to move the core into the second cavity, so that thesecond layer may be deposited on at least the second areas of the firstlayer.

However, it would also be conceivable for the rotary plate to carry outonly a rotational movement, in order to transport the cores positionedthereon in front of the respective openings of the cavities, and for thecavities to carry out the translational movement for receiving the corein the internal area of the cavities prior to the injection process andfor discharging the core out of the internal area of the cavities afterthe injection process.

It is also conceivable for the cores to be arranged on transportelements that are movable in a translational direction relative to thelongitudinal axis of the core, said transport elements being connectedto the rotary plate in order to introduce the cores into the respectivecavities or to take them out of the cavities upon the rotary movement ofthe rotary plate in order to orientate the cores in front of thecavities.

It is further possible that a chip, a further plastic element, ametallic element, a magnet, a transponder, an electronic or electricallyconductive element and/or a fluorescent element, which is arranged on orembedded in a film that dissolves and releases the element for use, isinserted in the first or second cavity and is over-moulded with thefirst or second layer or is injected between the first and second layersduring the first or second process step.

To this end, the element which is preferably arranged on a film or issurrounded by a film, is arranged for example in a predefined areainside the first cavity, in order to be either completely over-mouldedby the first layer, for example by the first area of the first layer, orin order to be only back-moulded for example with the second area of thefirst layer.

If the element is completely over-moulded, the film, which for examplesurrounds the element in order to protect it from contamination ordamage during transport and storage, completely dissolves, as a resultof which the element can now be used.

If the element is only back-moulded, the film will preferably notdissolve yet, since the element is not yet completely surrounded by theinjection mass which it is supposed to protect from contamination anddamage in the future. The film will in this case not dissolve untilduring the second process step, when the second layer isinjected/spray-applied onto the second areas of the first layer.

It is also conceivable for the element to be introduced into the secondcavity or deposited on the first layer until prior to the second processstep, in order to be surrounded or over-moulded only by the secondlayer.

By means of the elements embedded in the layers of the preform, forexample a simple identification of the containers made from the preformfor example at the point of sale becomes possible, or the elementssupport the subsequent manufacturing process by such information thatenables the container treatment plant to recognize which kind ofcontainer it is and which treatment steps are necessary for thecontainer.

Moreover, pigments such as for example lasers and/or colour and/ornano-pigments may be specially applied onto the surface of the preform,which are deposited for example onto the outer surface of the firstand/or second layer(s) after the first injection process or process stepor onto the outer surface of the second layer and/or the first area ofthe second layer after the second injection process for example by meansof a laser.

Since a preform generally known from the prior art preferably includes athread that is used to apply a corresponding closure cap onto thecontainer produced from the preform, in order to protect the contents ofthe container from unwanted contamination, it is also necessary to mouldsuch a thread onto the preform.

The thread is preferably moulded onto the first layer of the preformduring the first process step by means of the first layer or is mouldedonto the preform in a process step following the first and/or secondprocess step(s) using a plastic material that differs from the at leasttwo layers.

This means that the thread is formed either from the material of thefirst layer or from a material that differs from that of the first andsecond layers.

The thread preferably has no second areas that are covered by the secondlayer. However, it is also conceivable for the thread to be made fromthe material of the second layer.

Further, a preform is claimed which is produced using themulti-component injection moulding method described above.

The preform according to the invention for producing containers,including a sleeve-like mould body that has a thread on an open endwhich is located opposite the end closed in the longitudinal directionof the mould body, consists of at least two thermoplastic elastomerlayers, each of which has at least one inner surface and at least oneouter surface, wherein the layers have the same or different materialcompositions and wherein the first layer has a first area and at leastone second area extending partially in the circumferential direction ofthe preform, with the layer thickness of the second area beingsubstantially smaller than the layer thickness of the first area andwith the second layer covering the second area of the first layer orwith the first layer (2, 2 a) and the second layer (3) having anessentially identical layer thickness and being adjacent to each otherat least in the circumferential direction of the preform (1).

In a preferred embodiment example, the first layer and the second layerhave colourings that are at least partially different from each other.

Thus, for example, the first layer has a white colouring and the secondlayer has a red colouring.

Moreover it is possible for the first layer and/or the second layer tobe a hard component or a soft component.

Accordingly, for example, two layers may consist of a hard component ora soft component or the first layer is a hard component and the secondlayer is a soft component or the first layer is a soft component and thesecond layer is a hard component.

In one embodiment example, a film, a chip, a further plastic element, ametallic element, a magnet, a transponder, an electronic or electricallyconductive element and/or a fluorescent element is arranged within thefirst layer or the second layer and/or between the first layer and thesecond layer of the preform according to the invention.

Here, the film is preferably a PET film which surrounds for example anelement or an insert such as a chip or a Fresh controller and whichcompletely melts during the injection process due to the heat of theinjected plastic mass, in order to enable the element to be embedded inan area predetermined for the element.

The thread of the preform according to the invention includes at leastpartially a high strength material that is essentially different fromthe material used for the at least two layers.

It is further conceivable for the outer surface of the first area of thefirst layer and/or the outer surface of the second layer to have anessentially abrasion-resistant labelling or graphic which is applied bymeans of hot-foil stamping, pad printing, screen-printing and/or byusing a laser.

This labelling or graphic has to be applied to the preform in such a waythat, when the preform is later blown or stretched into a container, thecorresponding graphic does not run or distort. So that apart from theelements that are injected into the first and the second layer, thepreform can have additional identification and/or advertising markings,so that the preform as well as the later container will become easy toidentify.

In order to achieve for example a better grip or to optimise the feel totouch of the container or an extraordinary design or some enhancedfunctionality, such as for example enhanced standing stability of thecontainer even on an uneven surface, the outer surface of the first areaof the first layer and/or the outer surface of the second layer of thepreform according to the invention may have at least partially aroughened contour or a contour that has concave or convexcurvatures/concavities or prisms having pointed or rounded extensions.

Moreover, the preform according to the invention may have as a secondlayer for example a soft layer or a softer layer than the first layere.g. in the area of the bottom of the preform, in order to enable slipinhibition of the container for example on a smooth or uneven surface.

Further advantages, aims and characteristics of the present inventionwill be explained below by means of the description of the attacheddrawings, in which the preform according to the invention, by way ofexamples in different stages of manufacture, as well as an embodiment ofthe preform according to the invention are illustrated together with anelement on a PET film.

Components which in the figures at least essentially match with regardto their function, may here be identified with the same referencenumerals, however, these components will not always have to beidentified and explained in all of the figures.

In the figures:

FIG. 1 shows a schematic sketch of a first lateral view of an embodimentof the preform according to the invention having a first and a secondlayer;

FIG. 2 shows a schematic sketch in a view of a longitudinal sectionthrough the embodiment of FIG. 1 of the preform according to theinvention having a first and a second layer;

FIG. 3 shows a schematic sketch of a second lateral view of theembodiment of FIG. 1 of the preform according to the invention having afirst and a second layer;

FIG. 4 shows a schematic sketch of a first lateral view of an embodimentof FIG. 1 of the preform according to the invention having just onefirst layer;

FIG. 5 shows a schematic sketch of a second lateral view of theembodiment of FIG. 1 of the preform according to the invention havingonly one first layer;

FIG. 6 shows a schematic sketch of a cut-out of a first layer of theembodiment of FIG. 1 of the preform according to the invention;

FIG. 7 shows a schematic sketch of a principle structure of anembodiment of the preform according to the invention with an embossedfilm and element;

FIG. 8 shows a schematic sketch of the embodiment shown in FIG. 7 of thepreform according to the invention in an assembled condition; and

FIG. 9 shows a schematic sketch of an embodiment of the preformaccording to the invention having two layers arranged in a radialdirection next to each other on the core.

FIG. 1 shows a schematic sketch of a first lateral view of an embodimentof the preform 1 according to the invention having a first 2, 2 a, 2 band a second 3 layers. The sleeve-like preform 1 has a thread 5 in theupper area in the longitudinal direction of the preform 1, which threadwas preferably moulded onto the first layer 2 out of the material of thefirst layer 2. Below the thread there is a flange 6 which was alsopreferably moulded onto the first layer 2 out of the material of thefirst layer 2. The first layer 2 has a first area 2 a and a second area2 b. A second layer 3 lies directly on the outside of the outer surfaceof the second area 2 b of the first layer 2 in a radial direction andcompletely fills this area, so that the preform 1 has a uniform outersurface in the circumferential and the longitudinal directions.

FIG. 2 shows a schematic sketch of a view of a longitudinal section ofthe embodiment of FIG. 1 of the preform 1 according to the inventionhaving a first 2, 2 a, 2 b and a second 3 layers. In this view it canclearly be seen that the layer thickness or wall thickness of the firstarea 2 a of the first layer 2 is significantly greater than the layerthickness of the second area 2 b of the first layer 2. This differencein layer thicknesses is compensated by the second layer 3 which isarranged on the outer surface of the second area 2 b of the first layer2 in such a way that it completely fills the second areas 2 b up to thejoining areas 4, so that the preform essentially has the same layerthickness in the circumferential and the longitudinal directions overthe first 2 and the second 3 layers.

It can further clearly be seen in FIG. 2 that the thread 5 and theflange 6 are made from the material of the first layer 2 and are mouldedonto the first layer 2, and further that they are not covered by thesecond layer 3.

FIG. 3 shows a schematic sketch of a second lateral view of theembodiment of FIG. 1 of the preform 1 according to the invention havinga first 2, 2 a, 2 b and second 3 layers, with the second layer 3 beingclearly visible in this view, whereas the first area 2 a of the firstlayer 2 only occupies a minimum upper portion of the preform 1. Thesecond layer 3, which is disposed in or on the second areas (not shownhere) of the first layer, terminate without forming an overrun area intothe joining areas 4 with the first area 2 a of the first layer 2.

Consequently, the joining areas 4 or the joining area 4 is/are acircumferential edge which is generated relative to the formation of thesecond area 2 b of the first layer 2 and which separates the second area2 b of the first layer 2 from the first area 2 a of the first layer 2.

The term circumferential is to be understood herein to mean that theedge 4 or the joining area 4 has no beginning and no end but extends ina continuous way along the circumferential and/or the longitudinaldirection(s) as a function of the desired colouring of the preform 1.

FIGS. 4 and 5 each show a schematic sketch of a first and a secondlateral view of the embodiment of FIG. 1 of the preform 1 according tothe invention having only one first layer 2, 2 a, 2 b. FIGS. 4 and 5clearly show the areas 2 a, 2 b of the first layer 2, which differ fromeach other with regard to their layer thicknesses, with the first area 2a of the first layer 2 having a greater layer thickness than the secondarea 2 b.

The joining area 4 also forms here a circumferential edge 4 whichextends both in the circumferential direction and in the longitudinaldirection around the preform 1 and separates the first area 2 a from thesecond area 2 b.

To this end, the joining area 4 has a height which extends essentiallyradially outwards and which essentially corresponds to the difference inlayer thicknesses between the first area 2 a and the second area 2 b insuch a way that the layer thickness of the first area 2 a subtractedfrom the layer thickness of the second area 2 b essentially correspondsto the height of the joining area 4.

FIG. 6 shows a schematic sketch of a cut-out of a second layer 3 of theembodiment of FIG. 1 of the preform 1 according to the invention. If thepreform 1 shown in FIG. 5 is subdivided into two parts along itslongitudinal axis A and if then only the second layer 3 is taken fromthese two parts, the cut-out of the second layer 3, which is shown inFIG. 6, will be obtained.

The cut-outs of the second layer 3 can be very different as a functionof the desired colouring of the preform 1 or the later container, theconfiguration possibilities are unlimited.

FIG. 7 shows a schematic sketch of a principle structure of a furtherembodiment of the preform 1 according to the invention having anembossed film 10 and an element 11. The film 10 is here preferably a PETfilm 10, however, it may also be made from materials which dissolveunder certain ambient temperatures and may have for example a recess 14or a hole 14. The film 10 is normally pre-formed and will be depositedin this embodiment onto the outer surface of the second area 2 b of thefirst layer 2. This means that the film 10 or the element 11 is injectedbetween the second area 2 b of the first layer 2 and the second layer 3.To this end, the second area 2 b may have a protrusion 13 or a nose 13as well as a depression 12 or an embedding area 12. The embedding area12 has for example the same shape as the element, which is for examplean RFID chip or a magnet.

The pre-embossed film 10 with the element 11 is deposited onto thesecond area 2 b in such a way that the depression 14 is guided over theprotrusion 13 and the element 11 is inserted into the embedding area 12of the second area 2 b of the first layer 2. Subsequently, the secondlayer 3, which in FIG. 7 is only schematically shown, is injected ontothe film 10 with the element 11 during a further injection/spray-appliedprocess. The film 10 completely melts due to the heat or the pressure ofthe second injection mass, as a result of which only the element 11 willremain in the embedding area 12 between the second layer 2 and thesecond area 2 b of the first layer 2.

FIG. 8 shows a schematic sketch of the embodiment of the preform 1according to the invention, as shown in FIG. 7 in an assembled view, inwhich it becomes clearer that the film (not shown here) is no longerpositioned between the second layer 3 and the second area 2 b of thefirst layer 2, but only the element 11 is located in the embedding area12.

In this embodiment, the element 11 is located at the bottom end, in thevertical direction, of the preform or the bottom area thereof, so thateven after expanding the preform into a container, this element willremain in the bottom area of the container. Thus, the number ofcontainers transported over a predefined area may be detected forexample by means of a magnet scanner in the container treatment system.

FIG. 9 shows a schematic sketch of an embodiment of the preform 1according to the invention having two layers 2, 3 positioned next toeach other on the core in a radial direction. Here, the first layer 2 isnot formed to be continuous or extending around the entire circumferenceof the core, but has only a partial area of the preform, in this examplethe upper open area with the thread 5 and the flange 6, with the secondarea, i.e. the lower closed area of the preform 1 being formed by thesecond layer 3.

Thus, both layers 2, 3 have essentially the same layer thickness and areadjacent to each other not only in the longitudinal direction, but alsoin the circumferential direction of the preform 1.

Contrary to the examples described above, the second layer 3 does notrest here on an area of the first layer 2, but is injected on the coredirectly onto the areas remaining after the first injection process,i.e. onto the areas which are not yet covered with the first layer 2.

All of the features disclosed in the application documents are claimedas being essential to the invention in as far as they are novel over theprior art either individually or in combination.

LIST OF REFERENCE NUMERALS

-   1 Preform-   2 First layer-   2 a First area of the first layer-   2 b Second area of the first layer-   3 Second layer-   4 Joining area-   5 Thread-   6 Flange-   10 Film-   11 Element-   12 Embedding area-   13 Protrusion-   14 Depression

I claim:
 1. A multi-component injection moulding method for producing asleeve-shaped preform (1) which has at least two layers (2, 2 a, 2 b, 3)and an open end and an opposing closed end wherein the closed endcomprises an outer surface, said method comprising at least two processsteps including at least two cavities and at least one injection mouldcore that can be used for both cavities, said method characterised inthat: during the first process step, the first layer (2, 2 a, 2 b),which has at least one first (2 a) and at least one second area (2 b)extending partially in the circumferential direction of the preform, isinjected onto the injection mould core within the first cavity, whereinthe first cavity has at least one depression to form at least oneprotrusion of the first area (2 a), wherein said at least one depressionextends from an inner surface of the cavity essentially in a radialdirection towards the outside of the cavity and said at least oneprotrusion extends outward from surrounding surfaces of the first area,with the second area (2 b) having a substantially lower layer thicknessthan the first area (2 a), and during the second process step, in thesecond cavity the second layer (3) is deposited on the first layer (2, 2a, 2 b) which is located on the injection mould core in the secondcavity in such a way that only the second area (2 b) of the first layer(2, 2 a, 2 b) is completely covered by the second layer (3) and thefirst area (2 a) is formed by the at least one protrusion, wherein theclosed end of the preform comprises a continuous region of both thefirst layer and the second layer, and wherein the second layerconstitutes the outer surface of the closed end of the preform.
 2. Themethod as claimed in claim 1, characterised in that the second area (2b) of the first layer (2, 2 a, 2 b) has a layer thickness in thecircumferential and/or longitudinal direction(s) of the preform 1, whichcontinuously reduces at least in sections.
 3. The method as claimed inclaim 1, characterised in that the second area (2 b) of the first layer(2, 2 a, 2 b) has an outer surface as well as joining areas (4)adjoining the first layer (2 a) and joining areas (4) extendingessentially radially outwards and which bond intimately with an innersurface of the second layer (2 b) as well as with the joining areas (4)extending radially from the inner surface to the outer surface of thesecond layer (3) due to an adhesive or mechanical bond.
 4. The method asclaimed in claim 1, characterised in that the injection mould core, ontowhich the first (2, 2 a, 2 b) and the second (3) layers of the preform(1) are injected/spray-applied and which is located on a rotary plate,is moved into or out of the first and/or the second cavity by means ofan essentially translational movement of the rotary plate or thecavities along a longitudinal axis of the first and/or second cavity. 5.The method as claimed in claim 1, characterised in that the injectionmould core, onto which the first (2, 2 a, 2 b) and second (3) layers ofthe preform (1) are injected/spray-applied and which is located on arotary plate, is moved between the individual cavities by means of anessentially rotational movement of the rotary plate about an axis whichis parallel to the longitudinal direction of the cavity or vertical. 6.The method as claimed in claim 1, characterised in that a chip (11), afurther plastic element (11), a metallic element (11), a magnet (11), atransponder (11), an electronic or electrically conductive element (11)and/or a fluorescent element (11), which is arranged or embedded on/in afilm (10) that dissolves and releases the element (11) for being used,is inserted into the first or second cavity and is over-moulded with thefirst or second layer.
 7. The method as claimed in claim 1,characterised in that a thread (5) is moulded onto the first layer (2, 2a, 2 b) of the preform during the first process step by means of thefirst layer (2, 2 a, 2 b).
 8. The method as claimed in claim 3,characterised in that the joining areas (4) run out, as a result ofwhich the areas extend outwardly at an obtuse angle, wherein the secondlayer (3) is joined to the joining areas (4).
 9. The method as claimedin claim 1, characterised in that a chip (11), a further plastic element(11), a metallic element (11), a magnet (11), a transponder (11), anelectronic or electrically conductive element (11) and/or a fluorescentelement (11), which is arranged or embedded on/in a film (10) thatdissolves and releases the element (11) for being used, is injectedbetween the first and second layers during the first or second processstep.
 10. The method as claimed in claim 1, characterised in that athread (5) is moulded onto the preform (1).
 11. The method as claimed inclaim 10, characterised in that a thread (5) is moulded onto the preform(1) in a process step following the first and/or the second process stepusing a plastic material that differs from the at least two layers (2, 2a, 2 b, 3).
 12. The method of claim 1 wherein the second layer hasgreater tensile yield strength and enhanced heat distort resistance thanthe first layer.
 13. A multi-component injection moulding method forproducing a sleeve-shaped preform (1) which has at least two layers (2,2 a, 3) and an open end and an opposing closed end wherein the closedend comprises an outer surface, said method comprising at least twoprocess steps including at least two cavities and at least one injectionmould core that can be used for both cavities, said method characterisedin that: during the first process step, the first area (2 a) of thefirst layer (2) is deposited partially on the injection moulding corewithin the first cavity, wherein the remaining areas being covered bythe second layer (3) during a second process step within the secondcavity, wherein the closed end of the preform comprises a continuousregion of both the first layer and the second layer, and wherein thesecond layer constitutes the outer surface of the closed end of thepreform, wherein the first cavity has at least one depression to form atleast one protrusion of the first area (2 a), wherein said at least onedepression extends from an inner surface of the cavity essentially in aradial direction towards the outside of the cavity and said at least oneprotrusion extends outward from surrounding surfaces of the first area.14. The method as claimed in claim 13, characterised in that theinjection mould core, onto which the first (2) and the second (3) layersof the preform (1) are injected/spray-applied and which is located on arotary plate, is moved into or out of the first and/or the second cavityby means of an essentially translational movement of the rotary plate orthe cavities along a longitudinal axis of the first and/or secondcavity.
 15. The method as claimed in claim 13, characterised in that theinjection mould core, onto which the first (2) and second (3) layers ofthe preform (1) are injected/spray-applied and which is located on arotary plate, is moved between the individual cavities by means of anessentially rotational movement of the rotary plate about an axis whichis parallel to the longitudinal direction of the cavity or vertical. 16.The method as claimed in claim 13, characterised in that a chip (11), afurther plastic element (11), a metallic element (11), a magnet (11), atransponder (11), an electronic or electrically conductive element (11)and/or a fluorescent element (11), which is arranged or embedded on/in afilm (10) that dissolves and releases the element (11) for being used,is inserted into the first or second cavity and is over-moulded with thefirst or second layer.
 17. The method as claimed in claim 13,characterised in that a chip (11), a further plastic element (11), ametallic element (11), a magnet (11), a transponder (11), an electronicor electrically conductive element (11) and/or a fluorescent element(11), which is arranged or embedded on/in a film (10) that dissolves andreleases the element (11) for being used, is injected between the firstand second layers during the first or second process step.
 18. Themethod as claimed in claim 13, characterised in that a thread (5) ismoulded onto the preform (1).
 19. The method as claimed in claim 13,characterised in that a thread (5) is moulded onto the first layer (2)of the preform during the first process step.
 20. The method as claimedin claim 13, characterised in that a thread (5) is moulded onto thepreform (1) in a process step following the first and/or the secondprocess step using a plastic material that differs from the at least twolayers (2, 3).